explain xkcd - User contributions [en]

1162: Log Scale

2022-01-25T02:24:24Z

Eurydice: /* Explanation */ the old link was wrong

{{comic
| number = 1162
| date = January 18, 2013
| title = Log Scale
| image = log scale.png
| titletext = Knuth Paper-Stack Notation: Write down the number on pages. Stack them. If the stack is too tall to fit in the room, write down the number of pages it would take to write down the number. THAT number won't fit in the room? Repeat. When a stack fits, write the number of iterations on a card. Pin it to the stack.
}}

==Explanation==

This comic strip is a [[:Category:Tips|tip]], specifically the first [[:Category:Science tip|''science'' tip]]. As with most of Randall's tips, it is technically interesting for some applications but not very practical.

Uranium is stated to have 76 million MJ/kg, while the next highest material shown on the graph (gasoline) has 46 MJ/kg. Thus the uranium graph should be taller by a factor of 76,000,000/46 = 1.652 million. So, if the gasoline graph were 9mm in height, the uranium graph should be a bit more than 14.868 million mm tall, or nearly 15 km (9.2 miles) tall. Thus the need to fold the paper.

It should be noted that the method of extracting energy from the first 4 materials ({{w|combustion}}) is completely different from the method used with uranium ({{w|nuclear fission}}). If the technology existed to use {{w|nuclear fusion}}, then the first 4 materials would yield a higher energy density than uranium.

A {{w|Logarithmic scale|log scale}} is a way of showing largely unequal data sizes in a comprehensible way, using an exponential function between each notch on the y axis of a graph. So for example the first on a Y axis of a graph using a log-10-scale would be 1, then 10, then 100 and 1000 for the fourth. A {{w|logarithm|log/logarithmic function}} is the {{w|inverse function|inverse}} of a corresponding {{w|Exponential growth|exponential function}}. A log-scale version of the chart in the comic would look like this:

[[File:Log_Chart_1162.png | 600px]]

The log scale can also be abused to make data look more uniform than it really is. On a log scale the energy density of uranium looks larger than that of the other materials, but not dramatically so. The joke is that if one wanted to make their point "properly," they would go ahead and use ridiculous amounts of paper to show the difference between bars using a linear scale; this method would focus more on the shock factor of the differences in question, and less on actual communication/representation of data. Cueball seems to be passionate about the MJ/kg of uranium, so he would rather demonstrate the grandeur of the data than use a more efficient scale.

See {{w|Logarithmic scale#Common uses|these examples}} for well known day-to-day measurements which are measured on a log-scale.

The title text mentions computer scientist {{w|Donald Knuth}}; the fictional notation is a parody of {{w|Knuth's up-arrow notation}}. Using paper thickness as the basis for a log scale would probably give the exponential function a very large base. However, it can be noted that Knuth's up-arrow notation can handle numbers far, far larger than this paper stack notation; for example the number 3↑↑↑3, also known as Tritri<ref>https://googology.wikia.org/wiki/Tritri</ref>, very compact in up-arrow notation, would require a number of iterations pinned to the stack on the order of several trillion. 3↑↑↑↑3 , also known as Grahal<ref> https://googology.wikia.org/wiki/Grahal </ref>, would require a number of iterations that is not only too large to write down, but attempting to write that number using the same paper stack notation would require printing off a ''second'' stack of several trillion iterations just to hold the ''number'' pinned to the first stack. By repeating this multi-stack repetition, you reach the limit of up-arrow notation.

It should be noted that Randall has used log scales in past comics.

==Transcript==
:[A bar chart on a piece of paper, with a second piece of paper attached to it.]
:[Title of the bar chart] fuel energy density of different materials in megajoules/kg
:[Values of the first 4 bars on the paper] 19 24 39 46
:[The different bars for Sugar, Coal Fat and Gasoline and Uranium on a linear scale with the bar for Uranium exceeding on the attached stack of paper]
:[Labels of the 5 bars on the paper] Sugar Coal Fat Gasoline Uranium
:[The uranium bar on the chart goes off the page onto a huge strip of paper folded up into a stack slightly taller than Cueball.]
:[Value on the top end of the paper strip] 76 000 000
:[Caption below the panel:]
:Science Tip: Log scales are for quitters who can't find enough paper to make their point ''properly''.

==Trivia==
This comic was seen in the [[what if|What If?]] book, taken from "a certain webcomic".

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Bar charts]]
[[Category:Physics]]
[[Category:Statistics]]
[[Category:Science tip]]
<references />

Talk:928: Mimic Octopus

2021-12-31T17:37:50Z

Eurydice:

How does the mimic octopus manage to mimic multiple fish? Does it split it's own body up or something? '''[[User:Davidy22|Davidy22]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 13:30, 8 January 2013 (UTC)
:"When under attack, some octopuses can perform arm autotomy, in a similar manner to the way skinks and other lizards detach their tails. The crawling arm serves as a distraction to would-be predators. Such severed arms remain sensitive to stimuli and move away from unpleasant sensations.[23]"[http://en.wikipedia.org/wiki/Octopus#Defense] {{unsigned ip|173.245.48.113}}
::Fine, but in the SCUBA diver depiction, would it really need to rip parts out of itself to mimic bubbles? I don't think that that is quite necessary. {{unsigned ip|108.162.241.131}}
:::It could also hypothetically mimic bubbles by *actually blowing bubbles*. (No word on how it does this.) [[Special:Contributions/108.162.216.30|108.162.216.30]] 02:36, 2 January 2016 (UTC)Anon
::::Simple: This is a 2D {{w|Tomography|cut-out}} of the octopus mimicking the fishes or the scuba '''in 3D'''. It assumes a very complex figure, so that in the cut-out we only see the 2D pictures above. {{unsigned ip|162.158.83.144}}
:i always thought it was just a point of humour in the absurdity that a single octopus could mimic a group of fish -- just the same as it is for a rather small creature to mimic a full-size submarine [[User:Eurydice|Eurydice]] ([[User talk:Eurydice|talk]]) 17:37, 31 December 2021 (UTC)

For the record, octopus is from the Greek ὀκτάπους, a compound of ὀκτά (eight) and πούς (foot); πούς is a third declension masculine noun, whose plural is πόδες. Therefore, the etymologically correct plural of octopus should be octopodes, not (as Orson Scott Card suggests) octopoda, since πούς is not a neuter.
:Actually, it would be "octopuses", as it showed up ''after'' the regularization of English plurals to a final -s. As the video in the explanation explains, someone in the Victorian Grammarian Era "realized" it was "Latin" and pluralized it as such. This caught on and still haunts us to this day. "Octopdes" was coined around the same time by a more observant someone, who realized it was actually Greek. Personally, I avoid the whole trichotomy by saying "octopods". Unrelated etymologically, but has the same meaning and is unequivocally regular. Anonymous 08:08, 5 December 2013 (UTC)

Has anyone checked to see if the title text is true? Whether it is or not, this should be added to the description. [[Special:Contributions/108.162.212.18|108.162.212.18]] 11:53, 16 October 2015 (UTC)

What exactly is the pun here? [[Special:Contributions/199.27.133.78|199.27.133.78]] 00:53, 13 July 2016 (UTC)
:I don't know, either!?! "''Too many'' octopuses"??? {{unsigned ip|108.162.237.172}}

I had a very different impression of this comic when I first read it. I had never heard of a mimic octopus, and I assumed that the comic was making fun of calling a food dish "octopus" when it really wasn't. As in, a restaurant might feed you whatever they caught in a net and call it octopus, no matter how absurd it was. And if they ever did catch an octopus, they split it in two. Very cynical, but not nearly as cool. {{unsigned ip|108.162.246.115}}

I believe the third fish silhouette is actually a [https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjo1rua25jSAhWJ1IMKHU3XCUUQFggcMAA&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FGrouper&usg=AFQjCNGCdz2_bYFBDimJvFpFdG8sju4ljw&sig2=2D3silMR1tstIRSBihTGPA grouper], not a tuna. Sorry, Charlie.--[[Special:Contributions/162.158.74.237|162.158.74.237]] 03:26, 18 February 2017 (UTC)

I am not getting the "pun" of two mimic octopuses. Could anyone elaborate a little bit more? I never thought it as a pun, but rather implying that a mimic octopus, or any creature mirroring what it see, can only reveal its natural form by mimicking other mimic octopus. Though I think it makes sense, this is a bit different from other topics in xkcd, so I doubt it. 12:37, 22 August 2017 (UTC)

I agree with the above comment. Where's the "pun"? "Two Mimic Octopuses" doesn't sound like any other phrase. Maybe, at a stretch, "too many octopuses"? Moreover I don't think "… which is the pun of this comic" makes sense in any way. Comics don't all have puns, and comics with puns aren't limited to one. Perhaps it's a typo for "the point of this comic" or something? I'm going to remove that clause in 24 hours unless someone comes up with a convincing justification. [[User:AmbroseChapel|AmbroseChapel]] ([[User talk:AmbroseChapel|talk]]) 02:05, 13 September 2017 (UTC)

I am surprised that nobody mentioned the very similar mock identification charts such as [http://i.imgur.com/4ufx1.jpg this one] or [https://imgur.com/gallery/O5jlE7U that one]. Given the silhoutetted style of Randall's drawing, I'm pretty sure he had one or both in mind. [[Special:Contributions/141.101.105.204|141.101.105.204]] 15:36, 19 October 2017 (UTC)

The (visual) pun is that the one image out of all of them that actually looks like it could be an octopus, is actually not a (single) octopus. See the identification charts in the comment above for similar concept. [[Special:Contributions/172.69.62.148|172.69.62.148]] 20:38, 11 October 2019 (UTC)

Wait, they’re all mimic octopuses?

Always has been.

715: Numbers

2021-12-22T23:59:29Z

Eurydice: /* Explanation */ the old link was wrong

{{comic
| number = 715
| date = March 17, 2010
| title = Numbers
| image = numbers.png
| titletext = The typical internet user (who wants to share) has an IQ of 147 and a 9-inch penis. Better than the reverse, I guess}}

==Explanation==
This comic use the popular search engine Google to show how many hits (or web pages) are returned as relevant based on a given search replacing <X> by different numbers.

;Bottles of beer
:The top one is of the popular children's song {{w|99 Bottles of Beer on the Wall}}. In this song, the singers begin with 99 bottles and with each repeat of the verse, decrease the bottles of beer by one. The graph shows a slowdown at 66 bottles of beer, something highlighted. A spike occurs at 49 bottles of beer, which seems to be a popular variant (possibly due to 49 bottles taking about half the time that 99 would).

;Boy/girlfriends
:On the second row, the left graph represents how many girlfriends or boyfriends someone has had. They seem pretty similar, though the logarithmic chart may be working on that. There is a clear peak at four girlfriends.

;School grade
:In the middle of second row is a curve for how old (in grade) Internet users seem to be. Going purely by grade, the average is at 7th grade. However, using the notation of Freshman (9)/Sophomore (10)/Junior (11)/Senior (12), there's a notable resurgence.

;Penis length
:The graph on the far right of the second row describes Internet users talking about the lengths of penises that they have. 5-6 inches (~13-15 cm) is generally considered average, but it doesn't appear that way on the Internet. There is a general trend (also shown by the line), but the maximum, 9 inches (23 cm), peaks way above the trend line - indicating that guys think they can pull this one off, although 12 inches (30 cm) peaks way above the trend line as well. Probably because 12 inches equals a foot.

;Cup size
:The third row contains four graphs. The far left is the breast size of the Internet user. (This presumably refers to female users, since male breasts are not typically measured in cup size.) The actual breast size is generally considered a bell curve around a B or C cup, yet the hits on Google describe almost an exact opposite trend. Taken with the above male penis length and this describes a trend where either the "average" person posting information seems to embellish or the majority stay quiet. Typically those with small breast will complain, and those with large breast will complain or brag. Those that are content with a C cup do not need to do either.

;I have never had a boyfriend
:The second graph on row three is number of hits per (mostly) female Internet users talking about how old they are without having a boyfriend. There's a spike at 18. The comic was written in 2010; as of 2014 the spike does not exist. Google behaves very strangely in this case, as it shows two very different numbers for each search.
{|class="wikitable sortable"
!Age!!First number reported by Google!!Actual number of pages after advancing to the last one!!First number reported by Google after clicking on "More results from answers.yahoo.com"!!Actual number of pages after advancing to the last one (Yahoo Answers)
|-
|15||4||4||56,000||35
|-
|16||29,200||16||66,300||51
|-
|17||25,900||11||62,900||49
|-
|18||22,600||18||33,900||31
|-
|19||16,600||16||25,300||30
|-
|20||13,700||18||8,110||25
|-
|21||13,600||18||11,700||46
|}

;Glasses of water a day
:Third from the left in row three is the number of glasses drunk per day. Many "health authorities" claim that 8 glasses of water a day should be the most healthy. This {{w|Drinking_water#Requirements_for_drinking|common misconception}} is not supported by scientific research. This is the subject of [[1708: Dehydration]] and is also mentioned [[1853: Once Per Day]]. In both these six glasses of water is mentioned first rather than eight. (New research...)

;Number of lights
:On the far right is a description of the number of lights. The spike at four is due to a famous scene from {{w|Star Trek: The Next Generation}}, episode {{w|Chain_of_Command_(Star_Trek:_The_Next_Generation)#Part_II|Chain of Command Part II}} where {{w|Captain Picard}} answers that there are four lights, despite pressure to answer that there are five. This is itself a reference to {{w|George Orwell|George Orwell's}} novel {{w|Nineteen Eighty-Four}}, where {{w|Winston Smith}} is tortured until he "learns" to be unsure of the number of fingers being held up by his torturer, despite him only holding up four.

;Number of problems
:Bottom left is a reference to the popular {{w|Jay-Z}} rap song {{w|99 Problems}}. It is the only reason that ''100 problems'' only ends up second by more than a factor of 100.

;IQ
:Bottom right describes the {{w|IQ}} of the Internet goer compared to the average. By the definition of the test the average is 100 with a standard deviation of 15. However, the comic implies that the average claimed IQ closes in on 133 more than 2 standard deviations above the real average! This high average are thanks mainly to the million who has given their IQ as 147. There are four other peaks that are also labeled, and these peaks are the only other above 100,000 hits, but neither of these have much more than 200,000 hits. Apart from these five there are only 5 more with more than 50,000 hits. Note the log scale of the y.axis!
:Many studies have shown that people today would score a higher average than 100 if they took the earlier test - an effect know as the {{w|Flynn effect}}. However, new tests from today should still average out to 100, as an IQ of 100 is defined as the average of any given IQ test.
:The five labels: Why is 147 so popular? The {{w|maximum break}} in {{w|snooker}} is 147, but it is unlikely that this is known by enough to make a difference here. There is also a frequently repeated factoid that Albert Einstein scored an IQ of 147 but there's no real record or consensus of this. The 100 (the average) peaks out is obvious. 110 - ten more also makes sense. In general there are almost always more hits at every 5 and 10, than the two values before or after. 133 is a third of the way to 200, and also it will take you clear of the {{w|Mensa International|Mensa}} requirement for membership of 132 on the {{w|Stanford–Binet Intelligence Scales}}. Why 142 is popular is also difficult to say. Of course {{w|Answer_to_Life,_the_Universe,_and_Everything#The_number_42|42 is a special number}} for fans of {{w|The Hitchhiker's Guide to the Galaxy}}, so 142 for an IQ score could be helped to peak for this reason. Although then it is no longer 42... (But an IQ of 42 would be really bad!)
:The scale of the graphs x-axis is completely off. This can easily be seen from the labeled points. Whereas 100 and 110 is close to the mark, the point labeled 133 is much closer to 140 than 130 (at about 138) and the 147 point lies clearly past 150 (at around 152). It is, however, for sure the scale that is off as there are the correct number of points between all five labeled points.
:There is a clear point on the y-axis at 80, but then there seems to be a gap up to the next point, and there are also only 16 points between this first point and the point labeled 100. It thus seems that while there are in fact about 20,000 who claim as low an IQ as 80, then there are not enough who claims a score of 81-83 for them to be shown in this graph. The graph begins at around 80-90 hits because of the log scale so there could be some hits, but way less than the lowest point on the graph which lies close to 1000 hits. From an IQ of 84 and up to 168 there are a point for each IQ for a total of 86 points (with the point at 80).

;Title text
:The title text refers to the searches. It concludes that the average (male) internet user has a 9-inch penis and an IQ of 147. Humorously it continues to state that this is better than the reverse - having a 147-inch penis (over 12 feet or 3.7 m) and an IQ of 9 (only 2 % of the population have below 69).

==Transcript==
:Google Result for Various Phrases:
:{Each panel is a scatterplot of the described X against the number of Google hits, with trend lines. The scales vary.}

:<X> Bottles of Beer on the Wall
:[There are peaks at 1, 49, 73, and 99. A dip in the middle is marked "They lose steam at 66." After 99 is a steep dropoff. The largest peak is around 100,000 hits.]

:I've Had <X> Boy/Girlfriends
:[Both lines descend at roughly the same rate from 1 to 10, although the boyfriend graph is smoother; the girlfriend graph has a small peak at 4 and a small dip at 6. The peaks are between 100,000 and 1,000,000 hits.]

:I'm in <X>st/nd/rd/th Grade
:[The curve is a bell peaking at 7th grade and about 500,000 hits. A second line labeled "Including Junior, Senior, etc." follows the bell curve until the peak, then dips only slightly for 10th grade and resumes climbing.]

:I Have a/an <X>-Inch Penis
:[The line ascends shallowly from 100,000 hits for 3 inches to a peak of 180,000 for 9 inches, then descends steeply to 20,000 for 13 inches.]

:I'm a/an <X>-Cup
:[A has a few hundred thousand hits; the graph dips to a few thousand for C, peaks again around 100,000 for E, and then tails off.]

:I'm <X> and Have Never Had a Boyfriend
:[The graph is mostly a simple bell, starting and ending around 300,000 hits for 13 or 21, but there is a sharp peak of 700,000 at 18 (well above the trend line).]

:Drink <X> Glasses of Water a Day
:[There are barely any hits below 4 or above 12; between the two it rises steeply to about 1,000 hits, with a steep, narrow peak of 10,000 at 8.]

:There Are <X> Lights
:[The graph descends smoothly from several hundred thousand hits for 1 to about 10,000 for 10, except for a peak of about 1,000,000 for 4.]

:I Got <X> Problems
:[The plot is extremely jagged, with the largest peak of 10,000,000 hits at 99, another of 10,000 at 96, and 100 and 88.]

:My IQ Is <X>
:[A smooth curve starts and ends at a few thousand hits for around 85 and around 170, with the peak at several tens of thousands for 140, but there are several prominent outliers: 100, 110, 133, and 142 are all around 100,000 hits, and 147 is around 1,000,000.]

{{comic discussion}}
[[Category:Statistics]]
[[Category:Line graphs]]
[[Category:Penis]]
[[Category:Google Search]]
[[Category:Star Trek]]

Talk:628: Psychic

2021-12-20T05:07:12Z

Eurydice:

Tip: No one picks 50. [[Special:Contributions/75.69.96.225|75.69.96.225]] 01:35, 14 March 2013 (UTC)
:The '''Answer to the Ultimate Question of Life, the Universe, and Everything''' is 42. This comic is wrong ;) --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:52, 6 October 2013 (UTC)

Interestingly, it appears Megan was trying to trip Cueball up. The obvious choice would have been "42", a number with very geeky connotations, {{w|42_(number)#Popular_culture|to say the least}}. Megan may have thought of it immediately, known Cueball would suspect, and gone for the next higher number, 43. Of course, Cueball was smart enough to realize this simple trick, and knew Megan was, too. So he won anyway. {{unsigned ip|173.245.54.91}}

I seems that 37 (or 73) would be most not-random random. Though I cannot say, that sources are 100% reliable: [http://micro.magnet.fsu.edu/creatures/pages/random.html]
[http://catb.org/jargon/html/R/random-numbers.html]
[[Special:Contributions/141.101.88.219|141.101.88.219]] 08:57, 15 May 2015 (UTC) Koovert

Wait, if Cueball's probability to pick a specific number is 1/100 and Megan's probability to pick a specific number is also 1/100, wouldn't the probability of their picks being the same be 0.01%?
--[[User:Jogerj|Jogerj]] ([[User talk:Jogerj|talk]]) 02:11, 12 August 2015 (UTC)
::Yes, now multiply it by 100 because there can be 100 specific numbers. [[User:Anachor|Anachor]] ([[User talk:Anachor|talk]]) 10:17, 27 August 2015 (UTC)
::No, because you only have to have one of them match the other, not both of them match a number from some other source.[[Special:Contributions/173.245.54.34|173.245.54.34]] 07:07, 30 August 2015 (UTC)

Ooh, so the 17 thing is real after all! I've long since spotted it, but was never sure whether it's objective or just me preferentially noticing this number. Man, it feels good to be vindicated. [[Special:Contributions/141.101.104.82|141.101.104.82]] 05:11, 26 April 2016 (UTC)

Did anyone else read this that this trick worked and got Cueball a date to the movies? He took the lead, assuming that she would go along with because she was amazed by his psychic ability. [[User:Cosumel|Cosumel]] ([[User talk:Cosumel|talk]]) 05:35, 8 March 2020 (UTC)
:I think him saying "let's get to the movie" means they already had plans to go to the movies. Cueball probably just decided to stop and try out this trick out of the blue on their way there. [[User:Eurydice|Eurydice]] ([[User talk:Eurydice|talk]]) 05:07, 20 December 2021 (UTC)